Blade sharpening machine



March 21, 1939. w w HARTMAN BLADE SHARPENING MACHINE 3 Sheets-Sheet 1 Filed Aug. 9, 1937 INVENTOR ATTORNEY March 21, 1939. w w HARTMAN 2,151,204

BLADE SHARPENING MACHINE Filed Aug. 9, 1957 3 Sheets-Sheet 2 17 54 v 26 g 24 1 L 6 n2 "'3 12 2 Z? Z r 4 ATTORNEY March .21, 1939. w w HARTMAN 2,151,204

BLADE SHARPENING MACHINE Filed Aug. 9, 1937 3 Sheets-Sheet 3 MY/z'am h a/ffir/ /arfrlzan INVENTOR A'TTORNEY Patented Mar. 21, 1939 PATENT OFFICE BLADE SHARPENING MACHINE William Walter Hartman, Los Angeles, Calif.

Application August 9, 1937, Serial No. 158,090

5 Claims.

My invention relates to an improved blade sharpening machine, in which a rotatable grinder shaft carrying a grinding wheel is co-operatively arranged with reference to blade holding means, and in which a relative to and fro motion is in some manner established between the blade hold ing means and the rotatable grinding wheel, the axis of 'the grinding wheel being inclined or set at an angle with reference to the direction of said to and fro movement, and the grinding wheel being adapted to contact with and sharpen the thin beveled scalloped cutting edge of the blade during said to and fro movement of the grinding wheel.

It is immaterial whether the grinding wheel or the blade is moved to produce the to and fro movement, or whether they both are moved, so long as a relative to and fro movement is set up between them.

Also, this invention is applicable to sharpening any kind of blade, such as straight flat'blades, endless band blades, circular disk blades, or other kinds of blades, the adaptation of the machine for sharpening these various kinds of blades being well within the skill of an ordinary mechanic.

While it is an object of this invention to supply an improved eflicient blade sharpening machine .for general utility purposes, nevertheless the special and unique object of this invention is to provide a machine that will effectively sharpen a blade having a scalloped cutting edge, and do so in such manner that the portion of the cutting edge between the scallops will come up to a real sharp point, instead of a rounded curve as is produced by most blade sharpening machines because of the manner of their construction.

These and other objects of my invention will become clear by inspection of the appended drawings, and by consideration of the following description and claims.

While the substance of my invention may be embodied in machines of various types and forms to suit the designer or mechanic who constructs them, or the user, nevertheless in the accompanying drawings I have illustrated one preferred embodiment of the invention, which I will now describe in further detail.

In the drawings, Fig. 1 illustrates this form of my invention in elevation. Fig. 2 is a plan view of only a portion of the machine, in section along line X X of Fig. 1. Fig. 3 is a side view of the machine in section along broken line X X of Fig. 1, some parts of the mechanism in Fig. 3 having been omitted or broken away to more clearly illustrate other parts. Fig. 4 is an enlarged fragmental view of a portion of the blade feeding means, this view being taken in section along the broken line X --X in Fig. 3. Fig. 5 is an enlarged viewof one form of blade that may be sharpened in my machine. Fig. 6 is a transverse section of a part of the blade taken along line X X of Fig. 5. Fig. '7 is a plan view of a portion of the blade feeding and supporting means, this view being somewhat enlarged and being in section taken along line X" X' of Fig. 1. Fig. 8 is an end view of a section of the parts shown in Fig. 7, the section being taken along line X -X of Fig. '7. Fig. 9 is a fragmental view in plan of the rack and pawl mechanism which forms a part of the blade feeding mechanism used in this form of my invention, this rack and pawl mechanism being indicated in various positions in this figure. Figs. 10, 11 and 12 are diagrammatic illustrations showing some of the angular positions in which the grinding wheel can be held with respect to the blade in the'practice of my invention, as will hereinafter be more particularly described. Fig. 13 is a diagrammatic plan view showing some of the various positions in which the grinding wheel may be held in relation to the to and fro movement of the grinding wheel, in the practice of my invention, as will hereinafter be more particularly pointed out.

The substance of this invention, in part at least, can be understood by reference to Figs. 10, 11, 12 and 13. These are diagrammatic views showing various positions of the grinding wheel and the blade, in the practice of my invention. The blade is indicated by reference numeral I and the rotatable grinding wheel by reference numeral 2, the thickness of the grinding wheel especially in the vicinity of its grinding periphery 3, see Fig. 13, being relatively small when compared with the diameter of the wheel. As previously indicated my invention can be practiced in connection with any kind of blade such as a straight fiat blade, or an endless band blade, or a circular disk blade, or other types of blades that it may be desired to sharpen in conformity with my invention; and the blade supporting means of the machine may be such that that portion of the blade in the vicinity where it contacts the grinding wheel during sharpening may be held either straight as is more usual, or curved as is desired under certain circumstances; but in the preferred form of this invention I will illustrate it as practiced in connection with the usual type of relatively short straight blade, held straight in the vicinity where the grinding is done, the modifications needed for adapting the machine to the grinding of the other types of blades being regarded as well within the skill of the ordinary mechanic. With this understanding it may be remarked that in the plan view diagrammatically illustrating the parts in Fig. 13, blade I will beheld along the straight line AA, and in this figure reference numerals 2 2 and 2 indicate in plan some of the angular positions at which the grinding wheel 2 may be set, these positions corresponding respectively with the positions of the wheel shown in Figs. 10, 11 and 12. That is when the relation of the grinding wheel to the blade is as shown in Fig. 10, then the grinding wheel in plan, with reference to blade line AA, will be as illustrated at 2 in Fig. 13; or if it is desired to grind the knife with longer scallops than could be done by the parts set as in Fig. 10, then they can be changed to the setting illustrated in Fig. 11, the plan view of the grinding wheel in this setting being illustrated at 2 in Fig. 13; or if it be desired to make the length of the scallop still longer, then the grinding wheel can be completely turned around to the position shown in Fig. 12, the plan View of this position of the grinding Wheel being illustrated at 2 in Fig. 13. Settings such as these can be best procured by adjusting the grinding wheel rather than the blade line, and that is the mode used in the preferred form of my invention.

The actual grinding of the wheel along the scallops of the blade edge is accomplished by setting up in some manner a to and fro movement relatively between the blade and the grinding wheel, the direction of this to and fro movement, with relation to blade line or edge AA, Fig. 13, being transverse thereof and preferably, but not necessarily, along line B-B of Fig. 13. In the preferred form of my invention this toand fro movement is accomplished by moving the. rotatable grinding wheel, but in other embodiments of my invention the blade or blade supporting means can be moved to and fro instead of the grinding wheel, the latter then rotating in a fixed position. During this to and fro movement, however procured, it is obvious that the length of the contact that the grinding wheel makes along the length of the blade will substantially exceed the thickness of the grinding wheel at its grinding periphery 3, Fig. 13, thus illustrating how I succeed in grinding relatively long scallops on the blade instead of only short notches corresponding to the thickness of the grinding wheel. Also, the further the parts are twisted around with relation to each other, as respectively illustrated in Figs. 10, 11 and 12, the longer will be the arc of contact of the wheel along the blade, thereby illustrating how pitch a. of the scallops indicated in Figs. 10, 11 and 12,

- can be changed, using always the same wheel,

with no necessary change therein but by simply changing the angular relationship between the grinding wheel and blade as indicated. If the axis of the grinding wheel were always held parallel to the blade, only one scallop pitch could be produced by a given grinding wheel, and that pitch would correspond with the thickness of the wheel at its grinding periphery 3. In that casethe shape of the short scallop would be determined entirely by the transverse contour of the grinding wheel at its periphery, and if it were desired to uniformly maintain the shape of the scallop, it would be necessary to dress the grinding wheel frequently to maintain the desired scallop shape, but in my invention the shape of the scallop depends only slightly on the shape of the narrow transverse grinding contour of the wheel, and depends mostly on the diameter and angular relation between the wheel and blade as indicated in Figs. 10, 11 and 12. In any particular setting of the wheel to the blade, the changing shape of the wheel periphery due to wear, makes so little difierence in the shape of the scallop as ground, that the trifling difference can be disregarded. This is an advantage in favor of my invention in that it eliminates, or at least very greatly reduces, the necessity of dressing the grinding wheel and thereby makes it possible to produce and sharpen the blades more economically and more efficiently. Whether any particular embodiment of my invention will be constructed for only one given setting of the grinding wheel to the blade, or whether this setting shall be made adjustable to various positions, is a matter for the builder or user to determine, but I prefer the embodiment wherein the angle of inclination between the axis of rotation of the grinding wheel, and the direction of the to and fro movement, is adjustable from zero to ninety or to one hundred and eighty degrees, or within any intervening range desired. In speaking of the and fro movement, it is not necessary that these two directions actually intersect, because in some instances they would not as when the blade moves to and fro but it is suflicient that these two directions make an angle with each other when projected into a common plane, as in Fig. 13. In this figure dashed line a a, and line a a represents the axis of the grinding wheel in its respective positions 2 and 2 shown in this figure, and the axis of the grinding wheel when in position 2 would lie in line 3-3 in this figure. V

In referring to the to and fro movement set up relatively between the grinding wheel and the blade, it will be understood that this movement may be procured in any manner desired, as for instance a movement of reciprocation in a straight line, or of oscillation in an arc, or otherwise, but in the preferred embodiment of my invention as illustrated in the drawings I procure this to and fro movement by a construction that oscillates the grinding wheel to and fro bodily about an axis which in plan is diagrammatically indicated by shaft 4 in Fig. 13, and will be more fully described later.

The general character of my invention being now clear, I will proceed with a detailed description of its preferred embodiment as illustrated in the drawings.

By reference particularly to Figs. 1 and 3 it will be noted that the rotatable grinding wheel 2 is carried on grinder shaft 5, and this grinder shaft, which could be driven in any suitable manner as by pulley and belt, is in this embodiment the shaft of an electric driving motor 6 to which electric power is supplied through flexible conduit 1, see Fig. 1.

This grinding wheel and its driving motor is supported to oscillate to and fro on shaft 4, shown near the top of Fig. 1, this shaft being carried in a fixed position in a frame construction 8. On shaft 4 is oscillatively mounted the carrier member 9 which carries grinding wheel 2, grinder shaft 5, and motor 6, through connecting means which includes arm Ill, best seen in. Fig. 1, whereby the rotatable grinding wheel 2 and grinder shaft 5 are securely carried by carrying member 9 to oscillate to and fro in a fixed path about shaft 4.

In Figs. 1 and 3 the blade to be ground by wheel 2 is indicated at i, this blade being suitably positioned in a blade holding or blade. supporting means designated generally by reference numeral H, the details of which will be later described, it being understood that this blade supporting or holding means could be variously constructed to suit particular needs or types of blades, without departing from the spirit of this invention.

The manner in which grinder shaft 5, the axis of which is also the axis of grinding wheel 2, can

be adjusted or swung around tovarious desired positions with respect either to said to and fro: movement, or with respect to blade I, will now I be described.

The connecting means I0 passes up through the center of bored hub I2 of carrying means 9, and just below hub I2, member ID is threaded at I3, a nut I4 adapted to travel thereon being provided. At the extreme top of member ID there is another threaded portion I5, of reduced diameter, and thereon runs nut I6, a graduated dial I! being clamped on to member III between the upper shoulder thereof and nut I9. Extending between the upper shoulder I8 of member I0 and the top of nut I4 lies a tubular member I9 being threaded as indicated at at the top, and being also threaded at 2| at the bottom, this member l9 having a key 22 fastened therein. This key 22 is free to slide up and down in keyway 23 formed in the bored hub I2, and in fact the entire tubular member I9 is free to slide up and down in bored hub I2, but is prevented from rotating therein by virtue of key 22 running in keyway 23. To limit the up and down movement of tubular member I9 in hub I2, and to lock these two members together at any desired position, the spanner nuts 24 and 25 are furnished to run respectively on threads 20 and 2| of member I9. Projecting outward from the top of member I9, and fixed I thereto is an indicator pointer 26, which acting in conjunction with graduated dial II automatically indicates the angle through which the axis of the grinder shaft has been twisted, in any particular setting of the parts as previously indicated.

The foregoing construction being clear, it is now apparent that if it is desired to adjust or change the setting of the parts, for instance from that illustrated in Fig. 10 to the setting illustrated in Fig. 11 or 12, this is accomplished by loosening nut I4, see Fig. 3, whereupon member I 0 is free to rotate in the tubular member I9, and thereby when the grinder shaft and grinding wheel have been twisted around to the desired position with reference either to blade I, or to the to and fro motion of oscillation about shaft 4, the parts can again be locked in their desired position by screwing nut I4 up against the bottom of the tubular member I9, and the amount of twist or angularity of that setting can be read by pointer 26 on the index dial H. In the course of time the grinding wheel 2 will naturally become worn to somewhat smaller diameter, and this wear can be compensated for by what I term my distance adjustment between the grinding wheel and blade holder II, see Fig. 3. This distance adjustment is effected by loosening spanner nut 24 at the top of the sleeve member I9, thereby allowing this entire sleeve member I9 to be lowered through carrier hub I2, and this of course correspondingly lowers the connecting member II! which supports motor 6, grinding wheel 2 and grinder shaft 5, all these parts therefore being lowered toward the blade support II. The amount of this adjustment is made sufficient to compensate for the wear of grinding wheel 2, and the parts are then looked in this new adjusted position by tightening the lower spanner nut 25 against the bottom of the board carrier hub I2. This illustrates how bymeans of nuts I4, 24 and 25, and

the sleeve member I9, which is free to move up and down in, but not to rotate in the carrier hub I2, the angular adjustment of the grinding wheel 2, i. e., its twisting adjustment, and also the up and down distance adjustment of grinding wheel 2 with reference to blade holder II, can be procured more or less independently of each other, and how these adjustments when completed can be locked in desired position by manipulation of the aforesaid nuts.

I will now describe the mechanism by which the relative to and fro motion of the parts,which in this preferred embodiment of my invention is a motion of oscillation of the grinder wheel about shaft 4, is obtained. From the rear of frame 8 see Figs. 1 and 3, there projects a stationary arm 30, carrying in suitable bearings a drive shaft 3|, to which power may be supplied in any conventional manner desired but not shown in the drawings. Rigidly mounted on this shaft is bevel gear 32, meshing with similar bevel gear 33, the latter being rigidly mounted on shaft 34, which in turn is carried in bearings located in arms and 36, carried by frame 8, as will be apparent from the drawings, the function of this shaft 34 being to actuate the blade feeding means as will hereinafter be more particularly described. Returning to the drive shaft 3|, however, it will be observed that this shaft at its outer end carries a crank 31, having crank pin 38, all rigidly mounted on shaft 3| to rotate therewith. From crank pin 38 projects the conventional connecting rod 39 which at its other end, through pin 40, connects with arm 4| that depends from and is integral with the carrier member 9 and carrier hub I2. Obviously when drive shaft 3| rotates, this rocks connecting rod 39 back and forth in conventional crank-androd manner, and thereby the arm 4|, carrier hub I2, carrier 9, connecting member ID, electric motor 6, grinder shaft 5, and grinding wheel 2, are all rocked to and fro by a motion of oscillation about fixed shaft 4. The direction of this to and fro motion with relation to shaft 4 and the blade direction AA, is along the line B-B as best shown in plan in Fig. 13, this movement however, and the connection of the parts that produce it, being best traced in Figs. 1 and 3, the latter showing the line BB in the form of an arc about shaft 4 as a center. I prefer that the crank arm 31 be of sufficient length so that the extent of the to and fro movement of grinding wheel 2 be sufiicient so that during a portion of this movement the grinding wheel will be in grinding contact with blade I, and that during another portion of this movement the grinding wheel will be out of contact with blade I, this out-ofcontact relation being established either on one side or the other of blade I, or on both sides thereof, 1. e., at either or both ends of the stroke of the grinding wheel. It is during this out-of-contact interval that the blade feeding means feeds blade I crosswise of this to and fro movement, from one scallop of the blade to the next, as the to and fro movement of the grinding wheel proceeds, as will bepresently described. At this point in the description I wish to remark that best results from the invention are procured when the various parts above enumerated are so proportioned and arranged that a center line R,-R, see Fig. 1, passing out radially from and at right angles to shaft 4, will intersect at right angles the grinder shaft 5 at approximately the center of thickness of the grinding wheel 2. That is, the connecting means I0 may be so proportioned and shaped that when the angular addescribed, this angular adjustment will swing around the aforesaid center line RR. In order to practice my invention it is not necessary that the relationship just described be adhered to, but I prefer it and recommend it as desirable though not essential to the spirit of my invention. The relationship described produces a well balanced machine wherein the grinding wheel, during its to and fro movement, irrespective of its angular adjustment, maintains its proper normal relationship with the blade and blade feeding means, and the blade sharpening is effected with symmetrical and balanced results.

As previously indicated, the blade I is supported in the blade holder I I. As already indicated the means for holding or supporting the blade can be varied extensively, according to the character of the blade being sharpened, or according to the tastes or desires of the builder or user of the machine; but in the particular embodiment of my invention illustrated in the drawings this blade holder, being arranged for the conventional straight short blades, consists of a blade carriage 4,2, with blade I held or supported thereon, against the rear spacing shoulder 43, by means of a moderate pressure set up upon the blade by means of thin cap plate 44, fastened to carriage 42 by means of screws 45, see Figs. 1, 3, and 8, especially the latter. In this blade carriage 42 there may be arranged blade spacing pins 46, see Fig. l, spaced to fit into the end holes 41, of blade I, see Fig. 5, the uniform spacing of these holes and pins, and the co-relation of blade carriage 42 with grinding wheel 2, in view of the blade feeding means yet to be described being such that the successive scallops 48, see Fig. 5, are uniformly produced and sharpened in all blades handled by the machine.

The blade carriage 42 is made angularly adjustable on the carriage carrying member 49 by being frictionally bound thereto by nuts 50 which fasten the carriage 42 to the upstanding lugs 5| located to engage with the ends 52 of carriage 42, it being understood that these lugs 5| are preferably an integral part of the carriage carrying member 49, these relationships being best illustrated in Figs. 1 and 8, especially the latter. It might be remarked that the nuts 5!] operate on tie-rod 53 which passes lengthwise through the entire blade carriage 42 having one of the two nuts 55 at each of the ends of this tie-rod 53, see Fig. 1. The construction just described permits blade I to be angularly adjustable in its grinding contact or relationship to grinding wheel 2, as can be best understood by reference to Fig. 8. The adjusting feature just referred to permits the machine to control the degree of bevel, or sharpness, to which the blade is sharpened. That is, if the blade in Fig. 8 is adjusted to be quite horizontal, the bevel 54 will be long, and the blade very sharp but with delicate edge; while if the blade is adjusted to be more vertical, the bevel 54 will be shorter, the edge more blunt, i. e., less sharp, but more substantial.

The carriage carrying member 49 above referred to is supported in the ways 55 in the base 55 of the machine, see especially Fig. 8, thereby permitting this member 49, blade carriage 42, and blade I, to move in a fixed path along ways 55, to provide a blade feeding movement crosswise of grinding wheel 2, and crosswise of the direction of the to and fro movement of the grinding wheel 2.

In order to systematically feed these blade carrying members along this feeder path, blade feeding means is provided, which in this preferred embodiment of my invention consists of parts that will now be described. Onto member 49, see Figs. 7 and 8, there is fastened by means of screws 57, a rack 58, having rack teeth 59, see especially Fig. '7. pawl 61!, oscillatively supported on pin 5|, which is of one diameter along its lower portion I52, see Fig. 8, and approximately of the same diameter along its upper pawl carrying portion 63, but of enlarged diameter along the central portion I54 of this pin 5|. The lower end portion 62 of this pin is free to slide along slot 55 formed in base 56, and nut 56 is provided to permit locking pin 6| in any desired position in slot 65. Vfhen nut I56 is thus fastened, the pin SI is fixed in position, and pawl 55 may rotate about pin GI in counter-clockwise direction, as viewed in Fig. 7, when the rack teeth 59 are fed in downward direction as viewed in this Fig. '7. Tension spring 67, acting between pawl pin 68, and fixed pin 59, is furnished to keep pawl 60 normally engaged with the rack. In addition to thefixed pawl 50, there is also a traveling pawl It, oscillatively mounted on pin II which itself is fixed in the intermittently actuated feeder member I2. This feeder member I2 is adapted to move back and forth in groove I3, formed in base 55 of the machine, and a keeper, or strap, I4, fastened to base 56, by means of screw I5, is provided for the purpose of keeping feeder member 72 restrained in groove I3. The traveling pawl III is normally urged against rack teeth 59 by springlt acting between pawl pin TI and anchor pin I8, carried on member I2, see Fig. 'l. The feeder member I2 is intermittently actuated by contact with a cam I9, see Figs. 1 and 4, this cam being rigidly fastened to the bottom of the previously described shaft 34. This cam I9 is of circular contour over most of its periphery, except as to the raised portion extending radially therefrom. When this raised cam portion 80 contacts with feeder member I2, the latter moves to the left, as viewed in Fig. 4, or to the right as viewed in Fig. 1, this movement when transferred to the position of the parts as seen in Fig. '7 corresponding to a downward movement of feeder member I2. This last described movement of member I2, acting through pawl III, the latter contacting with rack teeth 59, obviously actuates rack 58, member 49, blade carriage 42, and blade I, in its crosswise blade feeding action, by an amount determined by the relative size of cam bump til, and the relative positions of traveling pawl I5 and fixed pawl 68, the amount of this movement being also determined by the length of the rack teeth 59. The proportion of the parts just described is of course such as to give the desired length of scallop 48 on the blade. After the cam bump passes over feeder member I2, a retrieving spring BI, acting between fixed pin 82 and a pin 83, permanently fastened into feeder member I2, as best seen in the lower left-hand corner of Fig. 1, serves to retrieve feeder member I2 against the circular portion of cam I9, and such retrieving action of the feeder member I2 of course carries with it the traveling pawl III, to cause this pawl to engage a new tooth 59 on the rack 58, this rack having of course been held in fixed position during this operation, by means of the fixed or non-traveling pawl 60. As best illustrated in Fig. 1, the entire carriage traveling system comprising carriage carrying member 49, blade carriage 42, blade I,

Co-operating with this rack is a fixed' and rack 58, is normally urged into a retrieving blade edge by line AA, and although this genaction against the pawls 60 and ill, by means of a retrieving weight 84, connected by cable 85 and hook 88 to the carriage carrying member 49, the cable 85 running over pulley 81. When the blade carrying system has made a complete traverse across the entire width of the blade, the carriage can be quickly retrieved to initial position by simply actuating manually lever 8, extending rearwardly from pawl 68, see Fig. 9, this lever 88 being manually shifted counter clockwise as viewed in this figure, and thereupon the projecting finger 89 comprising a part of arm 88, will contact arm 9! which is united integrally with traveling pawl 10, and both pawls 60 and iii will thereby be shifted from their full line position shown in Fig. 9, to their dotted line positions shown in that figure, the latter representing disengagement of pawls 60 and Hi from rack teeth 59. In this latter position of the pawls, the rack teeth and rack being free therefrom, the entire blade carrying system will be retrieved to its initial position under the influence of the retrieving weight 84, shown in Fig. 1, in a manner that will be selfevldent from the preceding description.

All of the blade feeding mechanism previously described is so oo-ordinated with the mechanism that produces the to and fro movement of the grinder wheel 2, that the intermittent feeding of blade 8, under impulse of cam bump 80, occurs during the interval when the grinding wheel 2 is not in grinding contact with blade I, and when the grinding wheel is in contact with blade I, the latter is not feeding because feeder member 12 is at that time riding on the circular portion If different scallop pitch is desired, that is different distance from point to point in the blade edge, then a different rack 58, having different spacing of the rack teeth 59, may be substituted for the one shown, and the stationary pawl pin Bl can be suitably changed with relation to its position in slot 85. Also bump 80, on cam 19, can be made sufficiently large to cover various pitch lengths that may be desired, or else, if preferred, a cam 19 can be provided to suit each rack 58 with the various tooth lengths that may be supplied on the various racks, This is one manner in which the pitch of the scallops in the blade 5, may be controlled.

In connection with Figs. 5, 6, 8 and 13, I wish to point out that the blade supporting means supports blade I in such relation to the grinding wheel 2 that the smooth face of the blade makes an angle with respect to the grinding wheel, to thus be non-tangential thereto, whereby a sharp bevelled cutting edge 54, is ground along the thin scalloped edge of the blade. This angle that the blade makes with the wheel, (or in other words the blade variance from tangential position) is small, and the smaller it is the finer andsharper will be the bevelled edge. Although small, this angle is nevertheless discernible, and it is understood that the immediate bevelled edge 54 of the blade is practically tangential to the grinding wheel, but this is not so of the smooth face of the blade behind the bevelled edge.

Also the fixed path controlling the to and fro motion that occurs relatively between the grinder shaft and grinding wheel on the one hand, and the blade supporting means on the other hand, is seen to extend in a general way transversely of the beveled blade edge 54. In Fig. 13 this motion is indicated by arrows 3-3, and the eral transverse motion, or path of motion, is shown approximately at ninety degrees with relation to the blade edge, nevertheless its direction can vary somewhat therefrom, as hereinbefore mentioned.

This now completes the description of a machine embodying a preferred form of my invention, and the foregoing description being ample, both as to the mechanism and mode of operation, it is believed that the character of my invention is now apparent therefrom.

The relationship of the grinding wheel 2, to the blade, during the to and fro motion described, results in forming real sharp points 9|, on the cutting edge of blade I, as best illustrated in Fig. 5. Blades having such sharp points are highly desirable in certain industries, such as the bread slicing industry, and others, and my invention disclosed herein contributes an efiicient and practical mechanism for readily procuring blades sharpened in this desirable manner, with minimum care of the grinding wheel, and with great uniformity of sharpening combined with great flexibility and range of scallop length, scallop depth, and bevel angle, and other desirable features that are apparent.

While I have described herein a preferred form of my invention, I am aware that extensive changes and modifications may be made therein, and I do not wish my invention to be limited except by the scope of the appended claims.

I claim:

1. A machine for grinding a scalloped, beveled cutting edge on the edge of a thin blade having a thin edge and a smooth face, said machine comprising in combination, a rotatable grinder shaft, a grinding wheel on said shaft, mounting means for said grinder shaft, blade supporting means adapted to support a thin blade in such manner that the thin edge of the blade is presented into grinding contact with the periphery of said grinding wheel and with the smooth face of the blade making an angle with respect to said grinding wheel to thus be non-tangential thereto to thereby grind a sharp beveled cutting edge along the thin edge of the blade, means for providing a to and fro motion along a fixed path relatively between said grinder shaft and grinding wheel on the one hand and said blade supporting means on the other hand, which said fixed path extends in a general way transversely of said blade edge that contacts with and is sharpened by said grinding wheel, said mounting means for the grinder shaft holding the axis of said grinder shaft tilted at an angle between zero and ninety degrees with respect to the general direction of said to and fro motion and the path of said to and fro motion being fixed to relatively sweep said grinding wheel and the thin cutting edge of said blade across each other in grinding engagement along a scallop indented along the thin edge of the blade to grind a sharp beveled cutting edge along such scallop and thence to out of contact position with respect to each other, whereupon the direction of the motion is reversed.

2. A machine for grinding a scalloped, beveled cutting edge on the edge of a thin blade having a thin edge and a smooth face, said machine comprising in combination, a rotatable grinder shaft, a grinding wheel on said shaft, mounting means for said grinder shaft, blade supporting means adapted to support a thin blade in such manner that the thin edge of such blade is presented to the periphery of said grinding wheel with the smooth face of the blade making an angle with respect to said grinding wheel to thus be non-tangential thereto to thereby grind, a sharp beveled cutting edge along the thin edge of the blade, supporting and guiding means for providing a to and fro motion along a fixed path for said mounting means, grinder shaft and grinding wheel which said fixed path extends in a general way transversely of said blade edge that is worked upon by said grinding wheel, said mounting means for the grinder shaft carrying said grinder shaft along said fixed path with the axis of said grinder shaft tilted at an angle between zero and ninety degrees with respect to the general direction of said to and fro motion, and the amplitude of said to and fro motion being sufiicient to sweep said grinding wheel from one side of the thin cutting edge of the blade into grinding engagement with said cutting edge along a scallop indented along said edge of the blade to grind a sharp beveled cutting edge along such scallop and thence in the same direction to out of contact position with respect to said blade on the opposite side of said thin cutting edge, whereupon such motion is reversed and repeated in reverse order.

3. A machine for grinding a scalloped, beveled cutting edge on the edge of a relatively thin elongated blade having a thin edge and a relatively wide smooth face, said machine comprising in combination, a rotatable grinder shaft, a grinding wheel on said shaft, a supporting shaft mounting means for said grinder shaft, said mounting means being oscillatively supported by said supporting shaft, blade supporting means adapted to support a relatively thin elongated blade having a relatively wide smooth face in such manner that the thin edge of such blade is presented to the periphery of said grinding wheel with the smooth face of the blade making an angle with respect to said grinding wheel to grind a sharp beveled cutting edge along the thin edge of the blade, means for oscillating said mounting means, grinding shaft and grinding wheel to produce a to and fro movement along a fixed path that extends in a general way transversely of said blade edge that is sharpened by said grinding wheel, said mounting means for the grinder shaft holding the axis of said grinder shaft tilted at an angle between zero and ninety degrees with respect to the general direction of said to and fro motion, and the path of said to and fro motion being fixed to sweep said grinding wheel from one side of the thin cutting edge of the blade into grinding engagement with said cutting edge along a scallop extending lengthwise of the thin edge of the blade to grind a sharp beveled cutting edge along such scallop and thence to continue to out of contact position with respect to said blade on the opposite side of said thin cutting edge thereof, whereupon such motion is reversed and repeated in reverse order.

4. A machine for grinding a scalloped, beveled cutting edge on the edge of a thin blade having a thin edge and a smooth face, said machine comprising in combination, a rotatable grinder shaft, a grinding wheel on said shaft, mounting means for said grinder shaft, blade supporting means for supporting a thin blade in such manner that the thin edge of said blade is presented to the periphery of said grinding wheel with the smooth face of the blade making an angle with respect to said grinding wheel to grind a sharp beveled cutting edge along the thin edge of the lade, means for setting up along a fixed path a to and fro motion relatively between said grinder shaft and grinding wheel on the one hand and said blade supporting means on the other hand said fixed path extending in a general way transversely of said blade edge that is sharpened by said grinding wheel, said mounting means for the grinder shaft holding the axis of said grinder shaft tilted at an angle between zero and ninety degrees with respect to the general direction of said to and fro motion, blade feeding means, the

path of said to and fro motion being fixed to relatively sweep said grinding wheel and the thin cutting edge ofsaid blade from one side of each other into grinding engagement along a scallop extending along the thin edge of the blade to grind a sharp beveled cutting edge along such scallop and thence in the same direction to out of contact position on the other side of each other, whereupon such motion is reversed and repeated in reverse order, and means for actuating said blade feeding means in coordination with said means for setting up said to and fro motion to intermittently advance said blade one scallop at a time with respect tosaid grinding wheel during an interval when said grinding wheel is out of contact with said blade.

5. In a machine for grinding a scalloped beveled cutting edge on the edge of a thin blade having a thin cutting edge and a smooth face, said machine comprising in combination, a rotatable grinder shaft, a grinding wheel on said shaft, mounting means for said grinder shaft, blade supporting means adapted to support a thin blade in such manner that the thin edge of such blade is presented to the periphery of said grinding wheel with the smooth face of the blade making an agle with respect to said grinding wheel to grind a sharp beveled cutting edge along the thin edge of the blade, means for setting up along a fixed path a to and fro motion relatively between said grinder shaft and grinding wheel on the one hand and said blade supporting means on the other hand which said fixed path extends in a general way transversely of said blade edge that is sharpened by said grinding wheel, said mounting means for the grinder shaft holding the axis of said grinder shaft tilted at an angle between zero and ninety degrees with respect to the general direction of said to and fro motion, adjusting means associated with said mounting means of the grinder shaft for adjusting said angle formed between the axis of said grinder shaft and the general direction of said to and fro motion, the path of said to and fro motion being fixed to relatively sweep said grinding wheel and the thin cutting edge of ,said blade from out of contact position on one side of each other into grinding engagement along a scallop extending along the thin edge of the blade to grind a sharp beveled cutting edge along such 

